Process and manufacturing equipment for preparing acetals and ketals

Abstract

A process for the preparation of acetals and ketals by reacting an aldehyde or ketone with an alcohol in the presence of an acidic catalyst and removing water by pervaporation. Manufacturing equipment for the preparation of acetals and ketones is also provided.

What is claimed is:  
     
       1. A process for the preparation of acetals or ketals which comprises reacting an aldehyde or a ketone with an alcohol in the presence of a solid acid catalyst at a temperature from about −50° C. to about 10° C., and removing water from the reaction product by pervaporation at a temperature from about 60° C. to about 130° C. using a hydrophilic membrane which is polymeric or ceramic. 
     
     
       2. A process for recovering acetals or ketals from reaction mixtures obtained by reacting aldehydes or ketones with alcohols in the presence of a solid acid catalyst at a temperature from about −50° C. to about 10° C., which process comprises subjecting the reaction mixture containing an acetal or a ketal together with water and urireacted aldehyde or ketone and alcohol to treatment with a solid base, being a weakly basic ion exchange resin, followed by pervaporation at a temperature from about 60° C. to about 130° C. using a hydrophilic membrane which is polymeric or ceramic to remove water from the reaction product. 
     
     
       3. A process as in  claim 1 , wherein the pervaporation retentate is subjected again to treatment with an acid under conditions that favour acetalisation or ketalisation, followed by treatment with a solid base, being a weakly basic ion exchanae resin, and removal of the water from the reaction product by pervaporation at a temperature from about 60° C. to about 130° C. using a hydrophilic membrane which is polymeric or ceramic. 
     
     
       4. A process as in  claim 3  wherein the treatment of the pervaporation retentate is repeated until substantially pure acetal or ketal is obtained. 
     
     
       5. A process as in  claim 2  further comprising (a) treating the pervaporation retentate with an acid under conditions that favor acetalisation or ketalisation, (b) treating the acetalisation or ketalisation product with a weakly basic ion exchange resin, and (c) removing water from the reaction product by pervaporation at a temperature from about 60° C. to about 130° C. with a polymeric or ceramic hydrophilic membrane. 
     
     
       6. A process as in  claim 5 , further comprising repeating steps (a)-(c) until substantially pure acetal or ketal is obtained. 
     
     
       7. A process as in any one of claims  1 - 4  and  5 - 6  wherein the solid acid catalyst is a strongly acidic polymer. 
     
     
       8. A process as in  claim 7  wherein the strongly acidic polymer is a polystyrene sulfonic acid. 
     
     
       9. A process as in any one of claims  2 - 4  and  5 - 6  wherein the weakly basic ion exchange resin used in the treatment with the solid base is a polystyrene resin carrying quanternary ammonium groups. 
     
     
       10. A process as in any one of claims  1 - 4  and  5 - 6  wherein 2,2-di(lower alkyl)-propane is prepared from acetone and a lower alkanol. 
     
     
       11. A process as in any one of claims  1 - 4  and  5 - 6  wherein 2,2-dimethoxy-propane is prepared from acetone and methanol. 
     
     
       12. A process as in any one of claims  1 - 4  and  5 - 6  wherein the pressure on the retentate side of the membrane is up to about 4 bar and the pressure on the permeate side of the membrane is about 1-500 mbar. 
     
     
       13. A process as in  claim 1  or  2  wherein heat produced in cooling the reaction mixture to a temperature from about −50° C. to about 10° C. for the acetalisation or ketalisation reaction is used to heat the reaction product to a temperature from about 60° to about 130° C. in the pervaporation. 
     
     
       14. A process as in  claim 7  wherein the weakly basic ion exchange resin is a polystyrene resin carrying quantemary ammonium groups. 
     
     
       15. A process as in  claim 8  wherein the weakly basic ion exchange resin is a polystyrene resin carrying quanternary ammonium groups. 
     
     
       16. A process as in  claim 7  wherein 2,2-di(lower alkyl)-propane is prepared from acetone and a lower alkanol. 
     
     
       17. A process as in  claim 8  wherein 2,2-di(lower alkyl)-propane is prepared from acetone and a lower alkanol. 
     
     
       18. A process as in  claim 9  wherein 2,2-di(lower alkyl)-propane is prepared from acetone and a lower alkanol. 
     
     
       19. A process as in  claim 14  wherein 2,2-di(lower alkyl)-propane is prepared from acetone and a lower alkanol. 
     
     
       20. A process as in  claim 15  wherein 2,2-di(lower alkyl)-propane is prepared from acetone and a lower alkanol. 
     
     
       21. A process as in any one of claims  1 - 4  and  5 - 6  wherein dimethoxybutane is prepared from methyl ethyl ketone.